“We know that the risk of perinatal mortality when BMI is over 40 is roughly doubled. This risk is quite U-shaped with BMI,” he told MJA InSight.

He said there was no evidence to suggest that Australia had any particularly unique trends when it came to perinatal mortality.

“But there is a problem with the classification system, which varies from country to country,” Professor Oats said.

Associate Professor Timothy Moss, National Health and Medical Research Council Senior Research Fellow at Monash University, said that while the Swedish study added to a body of international evidence on perinatal mortality risk, “it unfortunately doesn’t tell us about the causes of stillbirth or newborn death in women with high BMI”.

He told MJA InSight that another potential mechanism for stillbirth in obese or overweight women was the onset of sleep apnea, caused by airway occlusion.

“Researchers at the Mercy Hospital for Women and Melbourne University are investigating this possibility.”

Professor Moss said that maternal obesity was also associated with increased risk of a number of pregnancy complications.

“Some of these, such as pre-eclampsia, are also consequences of impaired placental development or function. Understanding how and why the placenta fails will be key to preventing stillbirth.”

Professor Wallace said that the biggest contributing factor to stillbirth was fetal growth restriction.

“If the baby’s growth is restricted, and the people looking after the baby don’t know it’s restricted, this increases risk of stillbirth.”

Professor Wallace said that when it came to trying to reduce stillbirth rates, paying more attention to the growth rate of the fetus was essential. There also needed to be better management of women who reported decreased movement from their baby.

“A recurrent finding is that a woman will report reduced movement [and then] come back a couple of days later with a stillbirth.”

He said another independent risk factor was also maternal age – not only are mothers having higher BMIs, but they are also getting older.

Professor Oats added that smoking and low socio-economic status increased risk too, and this collection of factors was a challenge in general practice.

“For GPs, there is some frustration. There’s not a lot you can do about socio-economic status, and often a BMI problem is already established when a woman becomes pregnant.”

However, Professor Oats said that it was important for GPs to first identify women in high-risk groups, like those with a high BMI or who are older, and then more closely monitor fetal growth rate and watch for conditions like pre-eclampsia.

One thought on “High BMI raises stillbirth risk”

These data should lead to reassessment of the wisdom of allowing (i.e. supporting via the MBS with public funding) obese women and their fertility specialists to spend taxpayers money on assisted fertility. Pregnancy is not a medical need and obesity impairs fertility, makes pregnancy more high risk, leads to higher still birth rates and worsens metabolic/cardiovascluar outcomes for children going forward. One needs to wonder why we spend money on buying a public health problem for the future. Given that funding in scarce in health and we are all being asked to consider avoiding low value interventions, maybe fertility treatement and assisted reproduction should be limited to women with a BMI under 30 at the time of treatment. They are no being told “no”, just being told that if it is so important to them, come back when you are in the target weight range. We don’t transplant livers into active drinkers, we ask people to lose weight to have a renal transplant….. we can’t afford emotion to cloud financial choices in health.